Do Not Compare COVID-19 (Coronavirus) To Seasonal Influenza

[42pines]

Covid-19 should not be compared to seasonal Influenza

It’s normal to look at the CFR (case fatality rate) of seasonal influenza when considering Covid-19. After all, 20-45 million get “the flu” every year. The numbers vary depending on the year. The “low” was the 2011-2012 season with 9.3 million cases and 12,000 deaths and the high was the 2017-2018 season with 45 million cases and 61,000 deaths._¹

Let us look at the worst of eight recent flu seasons. The CFR for that was 0.0014 meaning, 1.4 persons died per 1000 cases. Interestingly, if we look at the “best” of the past eight seasons (the “good” one) the CFR is 0.0013, almost the same number of deaths per thousand cases.

So, hold on to this thought...

Seasonal influenza’s average risk of dying is about one death per 750 cases.

I see and hear CFR for the Covid-19 repeatedly being quoted at around 2-3%. CFR currently (as of 2/27 12:23AM EST) is 3.4%. That is 2,810 deaths divided by 82,550 cases.

But to say that the CFR for Covid-19 is 3.4% is not wise. Why? Simply put, the CFR is not applicable are even a number that one can calculate since it's a "look-back" number.

For data current as of 2/27, click here.

CFR is a “look-back” rate

It is very useful when we look back to an epidemic/pandemic that has ended. For instance, when comparing the “good” 2011-2012 flu season to this season’s numbers. CFR is death rate / # of confirmed cases. To divide the known number of cases today by the number of deaths, we get 3.4%. But this is not wise to use because it assumes that ALL of the remaining cases (total cases today of 82,550, minus cases where the person has recovered or died) will be cured. This is “magical thinking.” Many of those remaining 46,488 will recover, but some will die.

In short, we won’t know the true CFR for another year or more. CFR is useless at this time, it will be helpful sometime next year.

Known outcomes

So, let us look at the cases with known outcomes, meaning the sum of the cases of those who have recovered plus those who have died. This population is composed of those 33,252 who have, to today, recovered plus the 2,810 who have died; thus, our population is 36,062. If we divide 2,810 (deaths) into our population of 33,252, we find an overall death rate of 8.45% or about 85 per one thousand cases with known outcome.

Please let that sink in for a bit. Today, looking at Covid-19 cases with known outcomes, 85 out of 1000 cases have died.

Should this hold, and it may, then 1 out of 12 cases will die.

Compare this to seasonal influenza where 1 out of 750 cases will die.

The death rate currently for Covid-19 is 62x the death rate of the average seasonal influenza.

These two illnesses do not compare, although we’ll really not know for a year or so, at which time we can look back to see what the true CFR rate was.

Let us look now at areas/countries to see the current death rate is, of those cases with known outcomes.

I’ll call the current fatality rate of known outcome cases: CFR-KO.

I shall call the population with known outcomes: PWKO

Total deaths / PWKO = CFR-KO or current death rate.

• World: 2801 / 36,062 = 8.45% or ~85 deaths per 1000 cases.
• Hubei Province: 2641 / 26,024 = 10% or ~100 deaths per 1000 cases.
• South Korea: 13/35 = ~37.2% or 372 deaths per 1000 cases.
• Italy: 14/54 = ~26% or 260 deaths per 1000 cases.

We see that regional epidemic outbreaks tend to drop in CFR-KO as time goes by. Whether the true “look-back” CFR will drop to 2 or 3% or some other number (lesser or higher) depends on many factors which are simply unknown. For instance, children appear to be much less at risk for Covid-19, and cases within Africa (other than the one in Egypt) seem oddly absent. Perhaps the virus does not do well in warmer climates. Perhaps the fatality rate will drop as we approach Summer in the Northern hemisphere—we do not know.

Perhaps the tendency of the media to quote the 2-3% theoretical CFR comes from the fairly recent 2009 H1N1 flu pandemic. The 2009 “swine” flu was very feared. It infected 10-200 million world-wide with estimates of death ranging from 105,700 to 395,600 and a CFR of 0.03% or 3%. (30 per 1,000 cases). (Wikipedia). It was expected to return far, far worse numbers.

The “swine” flu, which was the first pandemic of this century, turned out to be far less lethal than many expected. Triggle wrote in an article from December 10, 2009 titled, Swine flu less lethal than feared, "The swine flu pandemic is ‘considerably less lethal’ than feared, chief medical officer Sir Liam Donaldson says,” adding, “A study led by Sir Liam found a death rate of just 0.026% in those infected, the British Medical Journal reported.”²

Will we be lucky?

Perhaps we’ll be lucky this time, too, although I suspect we won’t be as lucky as we were for the “swine flu.”

[Wuzzie]

1 minute ago, toomuchbaloney said:

The WHO has adjusted the CFR to 3+

And 0.7% outside of Wuhan.

[42pines]

On 3/2/2020 at 6:03 PM, myoglobin said:

They report (as of March 02 at 2:50PM Pacific, 2020) that there have been a total of 90,305 cases worldwide with 3085 deaths. This would equate to a case fatality rate of around 3.41%.

Correct, but misleading. Simply stated: A case fatality rate of 3.41% stands only if every single case where the afflicted has not recovered, or died, will recover.

In other words, you are assuming that all remaining cases with unknown outcome will have no fatalities.

Nonetheless, my article's point is simply the "death" rate of the seasonal influenza over eight years is about one death in 750-1000 cases.

Using the 3.41% you have quoted means 34 deaths per 1,000 cases.

That means a death rate of about 34x that of the seasonal influenza.

Thus it is unwise for nurses to say: "oh, it's about the same as the flu."

On the other hand, the seasonal influenza has killed more this year already than has Covid-19 and we can lower that rate by immunization. Both are important subjects for nurses.

[42pines]

On 3/2/2020 at 12:43 PM, Wuzzie said:

What are you thoughts on this?

https://www.facebook.com/michael.zapor

Note: See following post to read Zapor's statement.

It's a neat article and I enjoyed it. It had some interesting sections:

"Because viral DNA has been isolated from respiratory secretions of exposed asymptomatic individuals, it is believed that not everyone who is exposed will become ill. The extent to which these individuals transmit SARS-CoV-2 to others is not yet known."

This is a potential "elephant in the room," unknown. This may be the reason that we are now seeing community cases in America.

"The overall estimated case fatality rate (CFR) appears to be ~2.3%, making it less deadly than some influenza strains."

The CFR is only useful "looking-back." To see what is occurring one must look at the death rate divided by the population with known outcome, meaning the population who have either recovered or died. We simply don't know about the rest of those cases, nor do we know about cases that exist that are not confirmed cases. I suspect that the eventual CFR will be between 3-4%, but that's a guess.

"To date, SARS-CoV-2 has shown itself to be a respiratory viral pathogen most commonly causing mild, self-limiting illness, with more severe disease limited to certain susceptible populations."

That statement is correct. It sounds quite mild, unless, of course, you are one of the 3,214 now dead.

This year's influenza season may kill more than Covid-19 does, it's been a harsh season, but eventually ~12-30 million Americans (based upon the past eight flu seanos) will have contracted the flu.

Should 12-30 million contract Covid-19, and if the fatality rate continues to be between 3-4% there could be 360,000 to 1,000,000 fatalities, which would be far worse than the typical flu season.

Could this happen? Yes. Might it not happen? Yes. Warm weather could stop Covid-19 in its tracks, or it might mutate to a more benign form as the H1N1 pandemic of 2010 (Swine flu) did.

[toomuchbaloney]

26 minutes ago, Wuzzie said:

And 0.7% outside of Wuhan.

It will be interesting to see how a country with poor health care access and high rates of chronic disease will fare.

[42pines]

On 3/2/2020 at 6:03 PM, myoglobin said:

They report (as of March 02 at 2:50PM Pacific, 2020) that there have been a total of 90,305 cases worldwide with 3085 deaths. This would equate to a case fatality rate of around 3.41%.

Myoglobin, I enjoyed your post and you know your history. I’ll only comment that, as most others do, you are not factoring in those cases that are “still out there, with undetermined outcome.” The 3085/90,305 is indeed the CFR. My point is that the CFR is only useful looking back after the epidemic has run its course.

Your numbers include those who have died + those who have recovered + about 35,000 cases whose outcome has yet been determined. To accept your 3.41% ALL in that remaining group of ~35,000 must recover with zero deaths. Do you think this is likely to happen?

We’re nurses, we like it when everyone survives. I suspect that some of those remaining 35,000 will not. I’m sorry that I’m not quite the optimist.

I do agree completely about what I call, “unintended effects.” China has become one of the world leaders in drug manufacturing, second to India. Even where drugs are made in America, pharmaceutical feedstock or some of it comes from China.

Here’s an obscure fact. ALL niacin (Vitamin B-3) is made in China. You might think “big deal—so what?.” Well, how about this, “ALL” mean over 22,000 tonnes! That’s 48 billion pounds. Now, you’re apt to say: “I don’t use vitamins.” My response would be: Did you have a sandwich for lunch today? (Most breads are enriched with B3)

Niacin shortages don’t bother me, but I do wonder about other supply line shortages for more critical med such as BP meds.

[Nurse SMS, MSN, RN]

It will also be interesting to see what happens now that China has released findings of two different strains of the virus, with one believed to produce worse symptoms/outcomes than the other.

[42pines]

3 hours ago, Nurse SMS said:

It will also be interesting to see what happens now that China has released findings of two different strains of the virus, with one believed to produce worse symptoms/outcomes than the other.

Got a link Nurse SMS? I'd like to see that.

[Nurse SMS, MSN, RN]

https://nypost.com/2020/03/04/chinese-researchers-say-2-types-of-coronavirus-could-be-infecting-people/

Many different news agencies reporting this. Google "China coronavirus two strains" to get a bunch of hits.

[Susie2310]

42pines, it seems that you have significant education/training in statistical methodology and epidemiology. Your OP says that you specialize in Occupational Health, and I recall your OP also says that you have a degree in Chemistry. Would you be willing to tell us about the education and courses you have taken, especially your education/training in statistics? My understanding is that you are also a nurse. Am I understanding correctly that you are an Occupational Health Nurse (or do you work in Occupational Health in another role) and also work in the ICU as a nurse? How did you decide to enter the field of Occupational Health?

[Nurse SMS, MSN, RN]

39 minutes ago, 42pines said:

Could this happen? Yes. Might it not happen? Yes. Warm weather could stop Covid-19 in its tracks, or it might mutate to a more benign form as the H1N1 pandemic of 2010 (Swine flu) did.

It could potentially die down over the Summer and roar back in the Fall, as the Spanish Flu in 1918 did. Lots of "what's going to happen" going on.

[Wuzzie]

45 minutes ago, 42pines said:

The CFR is only useful "looking-back." To see what is occurring one must look at the death rate divided by the population with known outcome, meaning the population who have either recovered or died. We simply don't know about the rest of those cases, nor do we know about cases that exist that are not confirmed cases. I suspect that the eventual CFR will be between 3-4%, but that's a guess.

Yes, you keep saying this but at this point I feel like I need to caution you to please remember that this may be a nursing forum but it is also open to a public who is already panicking about this subject. When you state death rates upwards of 30% you risk adding to their fear because they do not understand how you achieved that number. As nurses I absolutely believe we have a responsibility to educate but we also need to be sensitive to the fact that our words carry power. Your numbers, while interesting, contradict the data that is being put out by people who are epidemiological experts and perhaps we should leave the death rate figures to them for now. I do thank you for your efforts and this has been an interesting discussion.

[CommunityRNBSN, BSN, RN]

1 hour ago, 42pines said:

This was written eight days ago, submitted, but not posted as an article right away. I did make a more timely post that's the equivalent of this in "News."

Any article on this subject becomes "dated," almost immediately. When I posted this Italy was a tiny "blip" on the virus map, now it is the fourth largest "blip."

Let's look at Italy's number's today (3/4 10:18AM)

2502 confirmed cases; 79 deaths and 160 recovered.

There is an "urge" time simply divide deaths by confirmed cases: 79/2502=3.1%, this is the CFR (Case fatality rate).

Yet this number is completely meaningless, and here's why: Look at cases with "known outcomes" meaning that those afflicted have either died or recovered.

This population is the sum of those who have died + those recovered = 239

Of this population of cases with "known outcome" 79/239 = 33% death rate.

We do not know what will happen to most of the 2502 cases, but we do know that neither all will die, nor all will recover, with no deaths. This is why we cannot divide deaths/total cases..

Italy now: Current death rate of cases with known outcomes / 33%

You are correct, currently Italy is a "long way away from a 25% death rate," however it's actually in the direction opposite that you imply.

Over time, predictably, as cases with lesser severity appear, this number will likely fall.

To sum this up: It is inappropriate to simply divide deaths by total confirmed cases. It is more appropriate to divide deaths by the population whose outcome has been defined as dead or survived.

Where on earth are you getting your stats?? They are wildly different from anything by the CDC, WHO etc. Please post link.